This device relates to apparatus for the hearing impaired, and is more particularly directed to hearing aids. The invention is specifically directed to hearing aids of the type containing a rechargeable battery or power source, and containing means for recharging or reenergizing the battery or power source.
A number of rechargeable hearing aids have been recently introduced, and these have found favor particularly among those for whom, because of arthritis or other physical impairment, battery replacement is a problem.
As is well known in this field, conventional hearing aid batteries require periodic replacement, with a battery typically lasting no more than two weeks to a month. However, those hearing-impaired persons needing an aid are often afflicted with arthritis and may have trouble manipulating the battery into the case. Also, many hearing aid wearers often forget to purchase batteries, or find it inconvenient to get out to obtain them. Batteries also represent an ongoing expense, and many hearing-impaired persons are required to live on a rather stringent budget.
The incorporation of a rechargeable cell or battery into a hearing aid has alleviated this problem somewhat, and two types of rechargeable hearing aids have been introduced, the direct plug-in type and the inductively rechargeable type. The direct plug-in type requires the wearer to plug a charger directly into a socket on the hearing aid, and apply recharging current directly to the battery. The inductively rechargeable type of hearing aid is simply dropped into a recharger, which produces an AC magnetic field. This oscillating field is then converted, by the hearing aid, to a direct current which recharges the hearing aid battery. In both cases, the rechargeable battery is permanently incorporated, and is entirely within the case or shell.
An inductively rechargeable hearing aid and recharging stand is described in Mattatall U.S. Pat. No. 4,379,988. Aids of this type tend to have a high failure rate because of the large induction currents generated during a recharge cycle and also because of high temperature from inductive heating.
An eyeglass-type hearing aid which employs a solar or photovoltaic cell for operation is described in Passow U.S. Pat. No. 2,901,551. These aids have not become particularly popular, in part because of a tendency towards "motorboating" noise, and in part because the aid could not be made to look attractive.
While these types of aids have been an improvement, it often happens that wearer is away from home or may forget his or her recharger. Further, the wearer is limited as to where he or she can travel, as the recharger must be plugged into a standard power source, which may not be available if the wearer travels abroad, or for example, goes on an extended camping or fishing trip.